The invention relates to a dehumidifier, and more specifically, the invention provides a dehumidifier for removing moisture from the air in a pool enclosure.
Controlling indoor pool environments in a four season setting has been a costly and complicated job. While conventional ventilation systems and heat recovery systems appear to have a cost advantage over energy recycling equipment with respect to equipment cost, there are several problems associated with using a conventional ventilation system for a pool enclosure. First, a ventilation system works only when the humidity outside is substantially lower than the humidity on the inside. An indoor swimming pool can lose as much as 100 gallons of water through evaporation to the adjacent air every day. Traditional ventilation systems cannot remove this amount of moisture in a single day. Second, the operating cost of ventilation systems are higher in colder climates due to the need to heat winter air to an acceptable temperature for the enclosure. Outdoor air must be brought into the enclosure to decrease the humidity in the enclosure. Third, traditional ventilation systems will not control chlorine or eliminate chloramines in the air.
Excessive moisture in the air of the pool enclosure can cause several problems. The moist air encounters cooler surfaces such as windows, ceilings, or outdoor walls causing the air to cool and water to condense out of the cool air. The condensed water becomes a haven for fungus, mold and mildew which can contain potentially dangerous biotoxins. Furthermore, humid air is uncomfortable for any one in the swimming pool enclosure, except the swimmers. In addition, gaps in the ceiling or walls provide openings humid air to access building structural members. Condensation can cause water deposits to accumulate on structural members, unseen for years. These deposits can accelerate the deterioration of the structure.
One approach to dealing with the problem of humid air in a swimming pool enclosure has been to simply open the doors and windows of the enclosure and let external, relatively dryer air enter the enclosure. This xe2x80x9cpassivexe2x80x9d approach, however, only works on days when the outdoor air is at the same temperature as the air in the enclosure and is of lower humidity. These conditions rarely exist. Furthermore, the passive approach results in substantial energy loss, since the humid air of the enclosure contains latent heat energy lost by the water of the pool.
A second approach for dealing with the problem of humid air in a swimming pool enclosure has been to provide a ventilation system. Exhaust fans remove humid air while external air is heated or cooled to a desired temperature and transmitted to the swimming pool enclosure. However, the heating, ventilation, and air conditioning (HVAC) equipment required to accomplish this is expensive and difficult to operate. Furthermore, the equipment typically consists of relatively large and noisy exhaust fans. This approach will not work to dehumidify the air when the outdoor air has the same level of humidity as the air in the swimming pool enclosure.
A third approach to solving the problem is referred to as xe2x80x9cactive dehumidification.xe2x80x9d In an active dehumidification system, a blower draws air from the swimming pool enclosure through a dehumidifier coil which is chilled to maintain a surface temperature lower than the dew point. Humidity in the air condenses on the coil and drains. Both sensible and latent heat energy is recaptured by the refrigerant flowing through the dehumidification coil. Refrigerant is drawn into a compressor, compressed and forwarded to a pool water heater. The pool water heater acts as a condenser; heat is transferred from the refrigerant to the pool water. Active dehumidification systems also can include an air reheat coil. Refrigerant exits the pool water heater and travels to the air reheat coil to transfer any remaining heat available to air passing through the system.
Existing active dehumidification systems have several shortcomings. First, existing systems are unable to modify operating conditions to maximize efficiency and capacity. Specifically, existing systems will continue to operate at maximum blower capacity even when efficiency of the system decreases. The capacity of the dehumidifier coil capacity is based on surface area, temperature, and the velocity of air passed over the coil. As air velocity increases, the temperature of the coil will increase, and the capacity of the coil decreases. Therefore, it would be desirable to maintain a constant coil temperature. In addition, existing active dehumidification systems generally include a dehumidifier coil having six or eight rows. The six and eight row evaporator coils are virtually impossible to clean and must be replaced when dirty. Since refrigerant is circulated through the evaporator coil, replacement of a coil requires highly trained personnel.
The present invention provides an apparatus and method for removing moisture from air. The invention includes a refrigerant circuit passing through a first heat exchanger and an evaporator portion of a second heat exchanger. The invention also includes a heat sink circuit passing through the first heat exchanger of the refrigerant circuit and a third heat exchanger. Refrigerant moves along a first path formed by the refrigerant circuit. The first heat exchanger is exposed to an air stream. Heat is transferred from the refrigerant to the air stream as it passes through the first heat exchanger. The evaporator portion of the second heat exchanger is exposed to a heat sink fluid stream moving along a second path formed by the heat sink circuit. Heat is transferred from the heat sink fluid stream to the refrigerant as it passes through the evaporator portion of the second heat exchanger. The heat sink fluid moves from the evaporator portion of the second heat exchanger to the third heat exchanger. The third heat exchanger is exposed to the air stream and is positioned upstream with respect to the first heat exchanger. Heat is transferred from the air stream to heat sink circuit. Water vapor in the air stream condenses on the third heat exchanger. The air stream moves from the third heat exchanger to the first heat exchanger and is heated.
The present invention also provides a method and apparatus for directing air around the third heat exchanger to maximize the efficiency of the system. The third heat exchanger and the first heat exchanger can be positioned in a conduit. The conduit can be divided into first, second and third chambers by the first and third heat exchangers. The first chamber can be defined within the conduit between the inlet of the conduit and the third heat exchanger. The second chamber can be defined within the conduit between the third heat exchanger and the first heat exchanger. The third chamber can be defined within the conduit between the outlet of the conduit and the first heat exchanger. The invention can include a second inlet communicating with the conduit adjacent the second chamber to allow a second air stream to bypass the third heat exchanger and enter the conduit. The second air stream entering the second inlet is mixed with the air stream that has passed across the evaporator portion of the third heat exchanger. The invention can include a damper for opening and closing the second inlet and controlling the amount of air bypassing the third heat exchanger. The invention can also include a third inlet communicating with the conduit adjacent the third chamber to allow a third air stream to bypass the third heat exchanger and the first heat exchanger.
Other applications of the present invention will become apparent to those skilled in the art when the following description of the best mode contemplated for practicing the invention is read in conjunction with the accompanying drawings.